Deborah Hersman, chairman of the National Transportation Safety Board (NTSB), center, speaks during a news conference with John DeLisi, director of aviation safety with the NTSB, left, and Joseph Kolly, director of research and engineering with the NTSB, in Washington, D.C., U.S., on Thursday, Jan. 24, 2013. The design of Boeing Co.'s Dreamliner should have prevented battery incidents that prompted regulators to ground the plane on Jan. 7, Hersman said. Photographer: Andrew Harrer/Bloomberg via Getty Images

Deborah Hersman, chairman of the National Transportation Safety Board (NTSB), center, speaks during a news conference with John DeLisi, director of aviation safety with the NTSB, left, and Joseph Kolly, director of research and engineering with the NTSB, in Washington, D.C., U.S., on Thursday, Jan. 24, 2013. The design of Boeing Co.'s Dreamliner should have prevented battery incidents that prompted regulators to ground the plane on Jan. 7, Hersman said. Photographer: Andrew Harrer/Bloomberg via Getty Images

Deborah Hersman, chairman of the National Transportation Safety Board (NTSB), center, speaks during a news conference with John DeLisi, director of aviation safety with the NTSB, left, and Joseph Kolly, director of research and engineering with the NTSB, in Washington, D.C., U.S., on Thursday, Jan. 24, 2013. The design of Boeing Co.'s Dreamliner should have prevented battery incidents that prompted regulators to ground the plane on Jan. 7, Hersman said. Photographer: Andrew Harrer/Bloomberg via Getty Images

Deborah Hersman, chairman of the National Transportation Safety Board (NTSB), center, speaks during a news conference with John DeLisi, director of aviation safety with the NTSB, left, and Joseph Kolly, director of research and engineering with the NTSB, in Washington, D.C., U.S., on Thursday, Jan. 24, 2013. The design of Boeing Co.'s Dreamliner should have prevented battery incidents that prompted regulators to ground the plane on Jan. 7, Hersman said. Photographer: Andrew Harrer/Bloomberg via Getty Images